A chemical model to predict the formation of a semiconductor solid solution: New insights in the use of bulk and surface mechanochemical reactions

Abstract

A chemical model capable of predicting the formation of a semiconductor solid solution, via high-energy milling of powder precursors, is proposed. According to experimental findings provided by X-ray powder diffraction and X-ray photoelectron spectrometry, the model encompasses three major stages related to a series of oxygen levels, which are function of oxygen potential during milling. The initial step involves the formation of oxide mixtures, as evidenced by oxidizing highly reactive chalcogens (Se and Te) and re oxidation of PbO. In the middle step, which represents the largest process stage, Te or Se share electrons to act as Te (IV) and Se (IV) in order to form Pb complex chalcoxides. The formation of high purity Pb2SeTe semiconductor solid solution is detected at the final stage, in such stage the chalcogens act as reducing agents. Consequently, neither inert nor high vacuum atmospheres are required during the milling process. The model involves a quaternary interpretation whose predictions are validated with experimental findings, theoretical, and even analogous phases not reported so far in literature.